Furnace lining



A. G. CROLL FURNACE LINING Filed July 5, 1923 Oct. 25, 1927,

INVENTOR v f' ATTORNEY;

Patented Oct. 25, 1927.

UNITED STATES PATENT OFFICE.

ANDREW G. CBOIIIJL, F WEATHERLY, PENNSYLVANIA, ASSIGNOR TO THE ATLASPORTLAND CEMENT COMPANY, A CORPORATION OF PENNSYLVANIA.

FURNACE LINING.

Application filed .1u1y 5, 1923. Serial No. 649,533.

My invention relates to linings for apparatus in which materials aresubjected to a high degree of heat, such for example as the rotary kilnused in the making of cement,

5 blast furnaces, etc. The object of my invention is to provide a liningfor such apparatus which will be capable of absorbing and radiating heatto the materials being treated and at the same time act as an insulatorfor heat between the radiating surface or surfaces and the outer wall orshell of the apparatus. I will describe a lining embodying my inventionand then point out the novel features in claims. In the accompanyingdrawing, Fig. 1 is a view, partly in elevation and partly inlongitudinal section, showing a rotary cement kiln provided with oneform of lining embodying my invention. Fig. 2 is a transverse sectionalview on the line IIII of Fig. 1.

Fig. 3 is a detail view showing in side elevation and on an enlargedscale one of the blocks comprised in the lining shown in Figs. 1 and 2.Fig. 4 is an end view, and Fig. 5 a top view, of the block shown in Fig.3.

Similar reference characters designate similar parts in each of theseveral views.

Heretofore it has been the customary practice, in apparatus in which ahigh degree of 0 heat is employed, to line the kiln or other containerwith fire brick, which, among its other characteristics, acts as anon-conductor of heat. In such apparatus economy can be effected if thelining can radiate heat to the material coming in contact with it, andat the same time serve as aheat insulator between the radiating surfaceand'the outer wall or shell of the container. One feature of myinvention is the provision of a lining 40 having these twocharacteristics.

In .the accompanying drawing I have shown my invention applied to arotary kiln, such as is commonly used in making Portland cement. Thereference character A 4 designates the usual steel shell or wall of thekiln, which shell is mounted on rollers 2 and is rotated through themedium of gear wheels 5 driven by mechanism which is not shown in thedrawing. One end of the shell terminates in a housing 3 from which theraw material is fed to the kiln, while the other or delivery endterminates in a housing 4 which receives the treated material from thekiln, and from which hot gases are supplied to the kiln. The burningzone of the shell, that is, the zone between the housing t and a point6, is lined with fire-brick 7 of any suitable kind capable ofwithstanding the high temperature to which this zone is subjected. Atthe point 6 the shell may be lined with a single row 8 of fire-bricksimilar to that in the burning zone, except that it 1s deeper, asindicated in the drawing.

From point 6 to the feed end 3, that is, in the calcining zone, theshell A is provided with a lining B which, as here shown, comprisesunits or blocks b. In the articular embodiment of my invention ilustrated herein these blocks are spaced from the inner surface of theshell A by an auxiliary lining C made upof a suitable heat insulatingbrick.

Each unit or block b, as illustrated in Figs. 3, 4 and 5, issubstantially rectangular in shape, and these blocks are laid againstthe lining C with the long dimension extending around the circumferenceof the shell. The inner and outer surfaces of the blocks are accordinglycurved to conform with the curvature of the shell. The face or side ofthe block nearest to the shell A is preferably provided with a recess 9,thus leaving a flange 10 around the main or body portion of the entireblock in order to reduce the weight of the block. This flange is ofrigid heat-insulating substance, and may advantageously be made of oneart cement and three parts fine clinker, t e clinker being soaked inwater for approximately twelve hours before mixing with the cement. Theopposite face of the block is made of a heatresisting and insulatingsubstance, combined with a heat-conducting substance, which substancesmay be, as examples, cement and iron borings. Preferably the proportionsof these substances are varied in such manner that the percentage ofiron increases progressively from the flanged surface of the block tothe inner" surface 11, the percentage of cement decreasing accordin ly.For example the face 11 of the bIock may be divided into four layers 6b, b, and b,

and the proportions of iron and cement in these layers may besubstantially in accordance with the following table:

Parts by volume Layer h borings Cement b l 3 3 b I 3 2 b B 3 1%: b t 3 iIt will thus be seen that the portions of the block near the innersurface .11 are better conductors, and hence radiators, of heat than nthe portions near the flan es 10, and that the degree of conductivityecreases by stages from the former surface to the'latter.

The blocks 6 are attached to each other and to the auxiliary lining C bya suitable mortar which may consist, for example, of three parts fireclay and one part cement mixed with water to bring it to theconsistenoy'of a rather stifi paste. The blocks are usually laid up on aforming arch which holds them in place until a section of the kiln isfully lined so that the blocks become self-supporting, whereupon thearch is removed.

In the operation of the kiln, the raw material, such as crushed rock, isintroduced at the feed end 3 and travels toward the delivery end 4 dueto the rotation of the shell ,A, whereas hot kiln gases are supplied tothe shell at the delivery end and progress through the shell to the chney at the feed end; the moisture and other volatile matter contained inthe raw material are driven oil by the heat of the kiln gases which heatgradually decreases in intensity as thegases approach the feed end ofthe kiln. With a lining combining a heat insulating substance and aheat-conducting substance, the operation is improved in that the liningB absorbs heat from the kiln gases and gives up heatto the raw material.This increases the efficiency of the kiln, so that I am enabled toincrease the capacity of a kiln of given size, or to attain an equalcapacity with lower fuel consumption.

The burning zone 4-6 of the shell is not lined with blocks 6 having theradiating characteristics because in this zone the clinker or rawmaterial is in a very sticky condition so that it adheres to the lining7, forming a coating which protects this lining from the kiln gases. Itfollows, of course, that there would be no object in equipping this zonewith a heat-radiating lining such as the lining A.

Although I have herein shown and do scribed only one form of heattreatin apparatus and one form of lining embo ying my invention, it isunderstood that various Having thus described my invention, what I claimis:

l. A lining comprising a mixture of a heatinsulating substance and aheat-conducting substance varying in proportion progressively from arelatively small percentage of the heat-conducting substance to arelatively large percentage of the heat-conducting substance.

2. A lining comprising a mixture of a heat-insulating substance and aheat-conducting substance made up of layers varying in proportionprogressively from a relatively small percentage of the heat-conductingsubstance to a relatively large percentage of the heat-conductingsubstance.

3. A'lining for a heat treating container comprising a mixture of aheat-insulating substance and a heat-conducting substance varying inproportion progressively from a relatively small percentage of theheat-conducting substance adjacent the container wall to a relativelylarge percentage of the heat-conducting substance at the inner surfaceof the lining.

4. A lining for a heat treating container, made up of a plurality oflayers each comprising a mixture of aheat-insulating substance and aheat-conducting substance, the

percentage of the latter substance increasing progressively from thelayer nearest to the wall of the container to the layer exposed to thematerial being treated.

5. A lining for a heat treating container comprising a blockhaving abody portion made of a mixture of heat-insulating substance andheat-conducting substance, and a flange of heat-insulating substance forspacing said body portion from the wall of the container.

6. A lining for a heat treating container comprising a block having a.bndv portion and a flange for spacing said body portion from the wall ofthe container. said body portion being made of a mixture ofheatinsulating substance and heat-conducting substance, the percentageof heat-conducting substance increasing progressively by layerstrom saidflange to the opposite surface of the block.

ANDREW G. CROLL.

